The present invention relates to an apparatus and a method for fastening and holding insulation. In particular, the apparatus and method relate to fastening insulation around air ducts commonly used for heating and air conditioning. The apparatus comprises a flexible disk of relatively large surface area which, when attached by a fastener, flexes below the plane of the insulation and therefore applies force and tension to the insulation without reducing the insulation value of the insulation.
Very often wires are used for encircling, and thereby attaching, insulation to metal duct work in, for instance, air conditioning and heating applications. Such means for securing insulation to the metal duct work often results in "bellying" of the insulation or in some way not allowing the insulation to come into full contact with the duct work, reducing the efficiency of the insulation, and also enabling the insulation to completely become disattached from the ducts. This is particularly troublesome in air conditioning and heating applications because the insulation is commonly applied in rooms and other structural areas that are not meant to be heated or air conditioned. This either causes condensation, which destroys insulation value and damages walls and floors, or corrosion of metals including the duct work itself. Further, such areas tend to be inacessible once the duct work is installed, rendering re-fastening of the insulation extremely difficult.
In many cases duct tape is used to hold the insulation to the sheet metal duct work. Even more so than wire, tape has a tendency to loosen and the insulation is thereby separated from the duct causing the condensation and corrosion problems mentioned above.
Numerous innovations for fasteners, some for insulation, have been known in the art. For example, in the fields of plaster repair or roofing, various screw-washer combinations have been suggested. Even though these innovations may be suitable for the specific individualistic purposes to which they are designed, they differ from the present invention. The complexity of such devices and/or the inapplicability of such devices to accomplish the fastening of insulation to metal duct work makes the use of such devices incapable of solving the problems of insulation-to-duct-work attachment. Moreover, the use of the flexible disk of this invention for attaching insulation to air ducts is heretofore unknown in the prior art.
Spring-type washers, referred to as dished or conical washers, have been employed to secure screwheads and nuts against loosening, such as in U.S. Pat. No. 3,628,584 to Gutshall. Washers of this type are inapplicable to insulation uses because their diameter and surface area is too small, they lack the necessary flexibility and require substantial flattening force which would crush the insulation and destroy the insulation properties. Similarly, resilient pressure plates for attaching roofing nails and holding shingles, as in U.S. Pat. No. 5,407,313 to Bruins et al., have significantly smaller diameters than the present invention and require substantial force to flex them in order to hold the shingle. Each of these qualities, particularly in combination, are undesirable in holding air conditioning type insulation.
It is therefore an object of the present invention to provide an improved means for fastening insulation to an air conditioning or heating duct. It is a further object of the invention to provide a fastener having an area large enough to apply force in holding the insulation without distortion of the insulation upon fastening, and having the proper amount of flexibility to hold the insulation without crushing it and destroying the insulation properties.